Approximately 87% of women who undergo treatment for breast cancer are expected to survive for 5 years or longer. However, long-term, prospective follow-up studies of arm morbidity and its impact on functional status, mood, and quality of life (QOL) in these women are extremely limited. In fact, the study proposed in this grant application will be the first prospective longitudinal study of arm morbidity and patient outcomes following breast cancer treatment that has baseline data on arm morbidity outcomes prior to breast cancer surgery. Women for this study will be recruited from an ongoing NCI funded study that is evaluating the prevalence, severity, and timing of occurrence of neuropathic pain following breast cancer surgery and the factors that predict the development of these symptoms. Women (n=590) in the current study are recruited prior to surgery and are followed for 12 months. In this study, we propose to continue to follow these women for and additional 3 to 4 years depending on the time of enrollment. The specific aims of the proposed study are to: determine the prevalence, severity, and the timing of the lymphedema (LE);determine the prevalence and timing of occurrence of changes in shoulder mobility and changes in grip strength associated with LE;compare differences in anxiety, depressed mood, fatigue, sleep disturbance, functional status, and quality of life (QOL) in women who do and do not develop LE;and determine the factors that predict the development of LE. A secondary aim of this study is to begin to elucidate genetic markers for neuropathic pain and LE following breast cancer surgery. Findings from this prospective, longitudinal study will be used to identify women who are at high risk for arm morbidity and to guide the development of interventions for arm morbidity. Lay Summary: This study will determine what percentage of women develop LE after breast cancer surgery and the effects of LE on arm function. In addition, what places a woman at risk for LE will be evaluated.